Soil compaction process and device therefor



Dec. 3, 1968 G. MALAN 3,413,902

SOIL COMPACTION PROCESS ANDDEVICE THEREFOR Filed June 17, 1965 1 I T i L-- -i L..- .1

FIG. 3

Q9 2 INVENTOR.

GEORGE LMHLA/V AL zr/i w ATTORNEYS.

United States Patent 3,413,902 SOIL COMPACTION PROCESS AND DEVICE THEREFOR George L. Malan, 560 E. Rowland St., Apt. G3, Covina, Calif. 91722 Filed June 17, 1965, Ser. No. 464,715 Claims. (Cl. 94-48) This invention relates to the compaction of earth.

Earth compaction is of course fundamental to the sound construction of structures, especially massive structures such as power houses and the like. -If the earth is not suitably compacted, then the structure will not be stable. Because compaction is so fundamentally important, it has been the subject of intensive investigation and development for many years and it can fairly be stated that compaction of earth below about the top six to eight feet of the final grade has been developed to a reasonably good art, such that very heavy structures can reliably be built relying on compacted material more than six feet deep. However, the upper six to eight feet are themselves important, because if properly compacted they give significant support to the structure which is built atop it, without the need for pilings and the like to reach suitably compacted ground.

So important is the upper level of earth, that great pains are often taken to secure the necessary compaction therein. For example, in one technique, the earth is scooped out, and successive thin layers of earth are successively rolled down until the grade is reached. This is an acceptable and often used but very expensive procedure justifiable only for very expensive constructions. Another technique is to build up the earth six or eight feet higher than grade, then conduct an operation which successfully will compact earth more than six or eight feet deep, and then carry away the extra earth. However, this is also a very expensive technique.

In attempting to stabilize the upper portions of the underlying earth, numerous vibration techniques have also been devised. One which is frequently seen involves providing a heavy vehicle with oscillatory means which cause vibrations at predetermined frequencies to be transmitted into the earth. The problem here is that there needs to be a definite relationship between the vibrational frequency and the resonant frequency of the earth. Because the quality of the earth may vary from point to point, it is difficult to maintain this desirable frequency relationship and even then the relationship is less than optimum.

Another disadvantage of this vibrational technique is that the energy is broadcast into the earth without being opposed to a sufliciently resistive inertial mass. When this energy is broadcast into the earth, it is attenuated rapidly by the earth itself, and does not cause optimum compaction, because there is nothing against which a reaction occurs.

In accordance with this invention, there is submerged into the earth being compacted a source of vibratory energy. A reactive inertial mass rests on the surface of the earth, so that a substantial proportion of the energy is exerted on the earth between the energy source and the reactive mass, whereby optimum. compaction is attained with minimal dissipation of energy.

According to a preferred but optional feature of this invention, the reactive mass comprises a tractor having the dual purpose of pulling the energy source through the earth and itself providing the inertial mass at the surface of the earth.

According to still another preferred but optional feature of this invention, the energy source comprises a vibrator having an axis, which vibrator broadcasts energy in all radial directions, thereby compacting material be- 3,413,902 Patented Dec. 3, 1968 neath it, and also between itself and the reactive mass.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings in which:

FIG. 1 is a side elevation partly in cutaway crosssection showing the presently preferred embodiment of the invention;

FIGS. 2 and 3 are cross-sections taken at lines 2--2 and 3-3, respectively;

FIG. 4 is a right-hand view of FIG. 1; and

FIG. 5 is a side elevation, partly in cross-section showing an alternate technique for practicing the invention.

FIG. 1 shows a tractor 10 having a mass 11 which is schematically shown which includes all massive elements of the tractor such as its engine, frame, treads, power train, and the like, which mass is preferably mounted on treads 12 that themselves are driven by sprockets 13- which are suitably coupled to the engine (not shown). Any standard tractor will do for this purpose but as best shown in FIG. 4, it is desirable to distribute the reactive mass over a substantial area of the ground to be compacted. Therefore, track-laying tractors with wide treads are to be preferred over narrow treads, or those with tires, although both of these other types will function adequately. Such treads are well known in the art. The terms tread and track are used interchangeably herein and refer to any means for supporting the tractor. on the ground through which the weight of the tractor is exerted on the ground.

A mast 14 is connected to the tractor in a suitable manner so as not to impede the transporting of the tractor, and so that it can be inserted into the ground. The mast has a sharp leading edge 15 which permits the mast to be towed through the ground 16 which is to be compacted. The construction of this mast is similar to that used in conventional ripping teeth and the like, which devices are well known for cutting through earth below the surface. It is not unusual 'for such conventional devices to operate at depths of 5-6 feet, and. this depth is adequate for most purposes of this invention. With suitable power and weight relationships the mast may be made substantially longer for operating at greater depths.

The mast carries within it a pair of concentric conduits 17, comprising a pressure line 18 and an exhaust line 19 which may be connected to any suitable power source and exhaust as desired, for example to a source of compressed air and to atmosphere, or to the inlet and outlet of a hydraulic pressure source.

To the lower end of the mast there is connected a link 19a, which link provides a mechanical connection between the mast and a vibrator 20. This link carries within it continuations of lines 18 and 19, and provides mechanical and power connections with vibrator 20.

Vibrator 20 is an example of the presently preferred embodiment of transducer means for transmitting vibrational energy into the earth. Numerous other transducer means may readily be conceived, for example, pulsed diaphragm devices, but conventional vibrators of the class generally shown in Mal an Patents No. 2,743,090 issued Apr. 24, 1956, No. 2,891,775 issued June 23, 1959, and No. 2,988,337 issued June 13, 1961, have the advantage of producing substantial frequencies and energies in resistive environments. These vibrators have been broadly applied in dam building operations where they distribute concrete into molds. They are unlikely to stall in resistive environments, and their vibrational frequency can be controlled within broad ranges.

FIG. 3 indicates the general feature common to this class of vibrators. They include a housing 21 with a cylindrical race 22- having an axis 23. Within this race is a rotor 24 which is completely free and is adapted to roll around the inside of the race under forces derived from appropriate connections to pressure and exhaust. The lateral dimensions of the rotor are less than those of the race, so that this rolling motion is possible. These vibrators also include vanes, ports and the like the details of which are not germane to the instant invention. These details will be found in the aforesaid Malan patents. Their purpose is to control supply and exhaust of pressurized fluid from and to lines 18 and 19 to power the vibrator. Suffice it to say that the center 2-5 of the rotor rolls in a circular path around axis 23 while the external cylindrical surface 26 of the rotor rolls around the inside of the race.

Rotary motion of one part relative to another is also characteristic of crank-mounted oscillatory weights inside housing, which class of vibrator also would be suitable for the purposes of this invention.

As best seen in FIG. 4, the vibrations of the Malantype vibrators extend radially outward from the vibrator as shown by arrows 27 and extend completely around the vibrator in a plane 28 that is normal to axis 23, this plane being one of a family which is coextensive with the length of the vibrator. That portion of the energy which is discharged in are 29 is of considerable advantage in compacting earth to the side and beneath the vibrator. However, that energy which lies within arc 30 which is indicated by arrows 31 is of the greater importance to this invention, because this energy serves to compact the stratum of the earth between the energy source, i.e. the vibrator, and the treads acting as a reactive mass, This is a completely different system from simply broadcasting the energy into the earth where it is effective only on individual particles, and where it is attenuated by them. Instead, this is very similar to an anvil reaction wherein the applied energy is resisted through the workpiece.

Of course, directional control may be exerted over the vibrational area, and the energy transmitted only toward the reactive mass, but this arrangement usually is more trouble than it is worth.

The mast need not be extremely wide, and the swath which it cuts through the ground is soon compacted and closed again. The compaction is very efficient and is effective on the top six to eight feet, a result not practical at the present time.

FIG. illustrates that there need not be a structural interconnection between the vibrator and the reactive mass, nor need a specific mass be moved along the ground. Cable-laying machinery for laying cable 6 to 8 feet below the surface is well known. In FIG. 5, a cable 50 is shown already laid beneath the ground. Many such cables, lying parallel to each other, might be laid before the compaction is started. These cables may be connected individually or in any number to a winch 51. A vibrator 52 of the types already discussed is connected to the cable so that as the cable is wound onto the winch, the vibrator is pulled through the ground. Power conduits (not shown) for the vibrator are carried by the cable.

A reactive mass 53 rests on the ground. It can be of any dimensions, and could even be so large as to cover the area to be compacted, or it could be a vehicle such as shown in FIG. 1. Alternatively it may be drawn across the ground by winch 54 and cable 55 so as to remain over the vibrator as it is drawn through the ground. This constitutes another means for providing an opposed vibrator and reactive mass to compact earth between them.

This invention is not to be limited by the embodiments shown in the drawings and described in the description which are given by way of example and not of limitation but only in accordance with the scope of the appended claims.

I claim:

1. Apparatus for compacting earth comprising: a substantial reactive mass adapted to rest freely and otherwise unsupported directly and solely upon the surface of the earth to be compacted, and to cover a substantial area thereof; a mast attached to the mass and projecting downwardly therefrom into the earth; a vibrator attached to the mast beneath the surface of the earth and beneath the reactive mass; and propulsion means for moving the reactive mass along the surface of the earth, thereby moving the mast through the earth, and pulling the vibrator through the earth at a level and a location which are beneath the moving reactive mass, vibrational energy produced by the vibrator reacting on the earth between the vibrator and the reactive mass.

2. Apparatus according to claim 1 in which the reactive mass is a vehicle which includes propulsion means for moving the mass along the surface of the earth.

3. Apparatus according to claim 2 wherein said vehicle is a tracklaying vehicle with endless treads, the mast extending downwardly from and attached to said vehicle, the mast having a restricted forward edge adapted to plow through the earth as the vehicle moves forwardly.

4. Apparatus according to claim 2 in which said mast interconnects the vehicle and the vibrator so that the vibrator is drawn through the ground as the vehicle moves along the surface of the ground.

5. Apparatus according to claim 1 in which the vibrator comprises a free-rotor vibrator, wherein a rotor freely rotates within a race to provide vibrational energy around the full circumference of the vibrator in a plane which intersects the mass.

References Cited UNITED STATES PATENTS 2,138,103 11/1938 Jorgensen 9448 2,015,217 9/1935 Deniau 94-48 2,090,959 8/ 1937 Jackson 9448 2,215,888 9/ 1940 Swarthout 94-48 FOREIGN PATENTS 139,498 11/1950 Australia.

JACOB L. NACKENOFF, Primary Examiner. 

1. APPARATUS FOR COMPACTING EARTH COMPRISING: A SUBSTANTIAL REACTIVE MASS ADAPTED TO REST FREELY AND OTHERWISE UNSUPPORTED DIRECTLY AND SOLELY UPON THE SURFACE OF THE EARTH TO BE COMPACTED, AND TO COVER A SUBSTANTIAL AREA THEREOF; A MAST ATTACHED TO THE MASS AND PROJECTING DOWNWARDLY THEREFROM INTO THE EARTH; A VIBRATOR ATTACHED TO THE MAST BENEATH THE SURFACE OF THE EARTH AND BENEATH THE REACTIVE MASS; AND PROPULSION MEANS FOR MOVING THE REACTIVE MASS ALONG THE SURFACE OF THE EARTH, THEREBY MOVING THE MAST THROUGH THE EARTH, AND PULLING THE VIBRATOR THROUGH THE EARTH AT A LEVEL AND A LOCATION WHICH ARE BENEATH THE MOVING REACTIVE MASS, VIBRATIONAL ENERGY PRODUCED BY THE VIBRATOR REACTING ON THE EARTH BETWEEN THE VIBRATOR AND THE REACTIVE MASS. 